1. Field of the Invention
The present invention relates to a naturally circulated thermal cycling system, and in particular, the present invention relates to a thermal cycling system having an environmentally powered engine for circulating a fluid medium between a hot location and a cool location, for example, between the ground level where solar energy is available and the underground level where the temperature is relatively low.
2. Description of the Related Art
In general, a hot fluid, especially a gaseous fluid, fundamentally rises upwardly, and it is difficult to naturally deliver the hot gaseous fluid from a high location such as ground level to a low location such as an underground level. Accordingly, it has been necessary to use a power-operated fan or the like for forcibly delivering the hot gaseous fluid from a high location to a low location. In addition, it has been necessary to use a power-operated fan or the like for lifting the liquid fluid from a low location to a high location. Therefore, a considerable amount of power is consumed.
In a conventional thermal cycling system, such as a Rankine cycle system, the liquid fluid is heated so as to evaporate to a superheated gas in a boiler or an evaporator, then expanded, and condensed. The liquid fluid is then delivered to the boiler or the evaporator by a power-operated pump and again heated to repeat the cycle. Also in this case, a conventional thermal cycling system consumes a large amount of power.